"When you bad," boasts the young and beautiful, piss-and-vinegar-filled Muhammad Ali early in the documentary Soul Power, "you can do what you wanna do." The film, which takes too long to get to the meat of its matter, but captivates once it does, is an addendum to Leon Gast's Oscar-winning 1996 documentary When We Were Kings. Ali's bravado-soaked words, breezily tossed off after he disrupts a Don King press conference, also serve as an artist's manifesto for the film's musical acts: Celia Cruz, the Spinners, Fania All-Stars, Bill Withers, B.B. King, Miriam Makeba and more.

Culled by director Jeffrey Levy-Hinte from over 125 hours of footage that was shot by Paul Goldsmith, Kevin Keating, Roderick Young and Albert Maysles, and then relegated to the vaults after Gast didn't use it in Kings, Soul Power documents the three-day music festival that accompanied the iconic 1974 Muhammad Ali/George Foreman "Rumble in the Jungle" boxing match in Zaire. The concerts were meant to be a cultural exchange between African and African-American musicians (the late, great Cruz fiercely reps Cuba in a movie-stealing number), but were briefly imperiled after a Foreman eye injury forced a postponement of the fight. When finally mounted, the shows became the stuff of pop culture folklore. Given the ferocious power of many of the performances, and the dreary state of modern black pop (the recent death of Michael Jackson, not to mention Vibe, only underscoring the situation), Soul Power itself might well be subtitled When We Were Kings.

The film begins with lovely, if clichéd, day-in-the-life shots of ordinary Africans (a young mother strapping her two babies to her body before starting a long trek down a dirt road; a boisterous street bazaar), as well as press-conference and travel footage of the artists; a mid-air jam session, in which a member of Cruz's band improvises a Pepsi can as an instrument while Cruz keeps time by pounding the heel of her shoe against the overhead compartment, is especially cool. But this first act is largely padding, bogged down in the tedious chronicling of assorted logistics nightmares that accompany such an undertaking. It eats up time that could have been allotted for the actual performances. As it is, only headliner James Brown is allowed to strut his stuff on more than one song.

Info

Soul Power

Rated PG-13.

The irony is that Brown's is one of the least impressive of the performances. He's wonderful, but familiar. Much badder are Cruz and her sprawling, sexily raucous band; Bill Withers, with his sparse and aching acoustic performance of "She's Gone" (an especially brave choice of song given that most acts focused on mid- to uptempo numbers to rouse the crowd); and Miriam Makeba's "Click Song," introduced with a vigorous assertion of cultural pride ("It's not a noise, but my native tongue").

Infusing these performances with a political heft that resonates across eras is a press conference at which Ali dismantles a white reporter's utopian race rhetoric. With nationalistic counterattack, Ali calls out entertainers and athletes who don't dedicate themselves to the uplift of their people — the yin to the yang of James Brown's observation that "Dollars is what this thing is about. You cannot get liberated, broke."

Ernest Hardy is a regular film contributor at Voice Media Group and its film partner, the Village Voice. VMG publications include LA Weekly, Denver Westword, Phoenix New Times, Miami New Times, Broward-Palm Beach New Times, Houston Press and Dallas Observer.